SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cbc00b8a849092a5ffe32b48d1dd04fd1f82f0ec540605908e776460ef7f2e2' 
  AND token = 'a3WlXAO6ItRgTgRDpalPTUXlnZHqYY6LWiwq0mfHj28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}